Multispeed turntable drive



Sept. 16, 1958 E. WENNERBO MULTISPEED TURNTABLE DRIVE Filed March 4, 1953 fTzx/en'fok 5 EFL'K We-nweI-Lo United States Patent MULTISPEED TURNTABLE DRIVE Erik Wennerbo, Motala, Sweden, assignor to Industriaktiebolaget Luxor, Motala, Sweden, a corporation of Sweden Application March 4, 1953, Serial No. 340,197

Claims priority, application Sweden March 17, 1952 3 Claims. (Cl. 74-190) This invention relates to a phonograph device for imparting to the turntable different speeds of rotation, e. g. 78, 45, and 33% R. P. M.

A known device for this purpose has an intermediate wheel in the power transmission between the motor and the turntable, which wheel is adjustable in different height positions thereby being brought into engagement with different driving wheels, rotated by the motor, and further in every height position into engagement with the outer flange of the turntable.

However, it has proved that these intermediate wheels cannot for moderate costs be made with suflicient precision to eliminate uneven rotation of the turntable. The irregularities in the turntable speed is thereby especially noticeable at the lower speeds, i. e. 45 and 33% R. P. M.

In order to get rid of the intermediate wheel and the disadvantages attached thereto it is known to arrange the driving shaft of the motor vertically and supply this shaft with different driving wheels, which through an axial displacement of the motor are brought one in turn before a driving path arranged on the turntable, and by having the motor displaceable also in a horizontal direction the driving wheel in question may be brought into engagement with said driving path.

It has, however, proved that it is not so easy to attain the vertical displacement of the motor owing to its relatively great weight, which requires special arrangements to be unloaded, so that it does not unnecessarily load the control device with which the turntable speeds are to be adjusted.

The present invention has for purpose to eliminate the disadvantage mentioned and is based on a device without an intermediate wheel and having the motor fixed in a vertical direction.

The invention will hereinafter be described with reference to the accompanying drawing.

In the drawing:

Figure 1 is a side view of a device according to the invention.

Figure 2 is a top view of a detail included in the same device.

In the drawing 1 designates a base plate in a phonograph, the turntable 2 of which is in a known way rotatably mounted. In a nave 3, riveted to the turntable 2 and extending downwards, a flexible disc 4 is fixed, which in the present embodiment is formed as a cross of plate, e. g. steel plate or Phosphor bronze plate. On this cross a stiff, unflexible ring 5 is riveted, which along its periphery is supplied with a rubber rim forming a driving path 6.

Laterally of the disc 4 a motor 7 with a driving shaft 8 is arranged, which shaft extends upwards in a direction perpendicular to the plane of the turntable 2. The driving shaft 8 is supplied with axially arranged driving wheels 9, 10 and 11.

On each side of the ring near to the driving wheels 9, 1 0 and 11 a pair of guiding rolls 12 and 13, pressed against the ring 5, are arranged, which rolls rotate about shafts extending perpendicular to the plane of the turntable shaft. These guiding rolls are connected with a control device for the speed regulation and may by means of this device be displaced in a direction parallel to the plane of the driving shaft 8 of the motor. The guiding rolls 12 and 13 thereby move the ring 5 with the driving path 6 to different height positions before the driving wheels 9, 10 and 11, respectively, whereby the movement of the ring 5 to the first mentioned and last mentioned positions takes place through deformation of the disc 4.

When the control device is adjusted so that the details are brought to the positions according to Fig. l, where the driving path 6 is before the driving wheel 10, the phonograph is according to the present embodiment adjusted for playing 45 R. P. M. records, while an adjustment of the control device, so that the guiding rolls 12 and 13 press the ring 5 with the driving path 6 upwards to a position before the driving Wheel 11, means that the phonograph is prepared for playing 33 /3 R. P. M. records. Finally an adjustment of the control device, so that the guiding rolls l2 and 13 press the ring 5 with the driving path 6 downwards to a position before the driving wheel 9, means that the phonograph is prepared for playing 78 R. P. M. records.

In order to bring the different driving wheels in engagement with the driving path 6 the motor is displaceable in a horizontal direction.

The flexible disc 4 has here been formed as a cross. The disc may naturally also be made of a number of metal strips, which are fastened to the nave 3 and extend radially outwards from the nave and in the ends opposite to the nave are fastened to the ring 5. The disc 4 may instead be made as a whole disc of metal or steel plate or of any durable cardboard, e. g. fibre cardboard.

The driving wheels 9, 10 and 11 may naturally be replaced by a single cone-shaped driving wheel without departing from the spirit of invention. Several other embodiments than are here described are of course also possible within the scope of the appended claims.

What I claim is:

1. In combination a phonograph having a base plate and a turntable, means mounting the latterfor rotation on a vertical axis, said turntable comprising a record supporting plane surface above the base plate of the phonograph, a flexible disc arranged below the plane of the base plate concentric to and fixed to said turntable, a stiff, unflexible ring arranged on the outer periphery of said flexible disc, a rubber driving rim on the outer edge of said ring, a single speed driving motor arranged with its shaft upright outside said driving rim, a driving wheel with axially different diameters on said motor axis adapted to frictionally engage said driving rim of the ring, vertically displaceable guiding means arranged to engage said un-flexible ring near to said driving Wheel, whereby a vertical movement of said guiding means will deform said flexible disc and move said unflexible ring with said driving rim before axially different parts of the circumference of said driving wheel.

2. In combination a phonograph having a base plate and a turntable, means mounting the latter for rotation on a vertical axis, said turntable comprising a record supporting plane surface above the base plate of the phonograph, a flexible disc arranged below the plane of the base plate concentric to and fixed to said turntable, a stiff, unflexible ring arranged on the outer periphery of said flexible disc, a rubber driving rim on the outer edge of said ring, a single speed driving motor arranged with its shaft upright outside said driving path, a driving wheel with axially different diameters on said motor shaft adapted to frictionally engage said driving rim of the ring, vertically displaceable rolls on opposite sides of said ring near to said driving Wheel and with their cylindrical surfaces pressed against said ring, whereby a vertical movement of said rolls will deform said flexible disc and movesaidunflexible ring with said driving rim before:

axially diiferent parts of the circumference of said driving Wheel.

3. A device as claimed in claim 1, werein the flexible disc consists of metal strips radiating from the rotational center of the disc.

References Cited in the file of this patent UNITED STATES PATENTS Harrison July 14,

Guedon Sept. 2,

Simonson Jan. 29,

FOREIGN PATENTS Great Britain Sept. 4,

Great Britain Nov. 11, 

